Last year I wrote an experimental sbt plugin called sbt-projectmatrix to improve the cross building in sbt. I've just released 0.2.0.

building against multiple Scala versions

After adding sbt-projectmatrix to your build, here's how you can set up a matrix with two Scala versions.

ThisBuild / organization := "com.example"
ThisBuild / scalaVersion := "2.12.8"
ThisBuild / version      := "0.1.0-SNAPSHOT"
 
lazy val core = (projectMatrix in file("core"))
  .settings(
    name := "core"
  )
  .jvmPlatform(scalaVersions = Seq("2.12.8", "2.11.12"))

This will create subprojects coreJVM2_11 and coreJVM2_12.
Unlike ++ style stateful cross building, these will build in parallel.

split a subdirectory into a new repo (simple case)

git clone --no-hardlinks --branch master originalRepoURL childRepo
cd childRepo
git filter-branch --prune-empty --subdirectory-filter path/to/keep master
git remote remove origin
git prune
git gc --aggressive

Change originalRepoURL, master, and path/to/keep to appropriate values. Use -- --all to handle all branches.

split a subdirectory into a new repo (complex case)

This is a second post on installing your own JDKs on Travis CI. Previously I've written about jabba.

Today, let's look at SDKMAN!, an environment manager written by Marco Vermeulen (@marc0der) for JDKs and various tools on JVM, including Groovy, Spark, sbt, etc.

AdoptOpenJDK 11 and 8

Update 2020-09-23: Updated the regex of version number.

Spotify: https://open.spotify.com/user/1235450353/playlist/0guisAxA5Q2WO6biLJqdU0...
YouTube: https://www.youtube.com/playlist?list=PLSUh6oJ5ZotUlIMwWcbtV7FRTEzHqYm_7

2h 58m

track list

• Mbr / Ajisai - Ametsub
• Win In The Flat World - Lorenzo Senni
• Opal - Four Tet Remix - Bicep, Four Tet
• ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ৢ؞ؖ؞ - △▃△▓
• Recursion - Throwing Snow
• Opal Waltz - Supernaive
• Turnhalle - Barker & Baumecker
• #17 - Aphex Twin
• Good Winds - Efdemin
• Stingray Nebula - OUER

Ancillary Justice by Ann Leckie
My rating: 4 of 5 stars

'Ancillary Justice' is written in a first-person narrative as the AI of thousands of years old starship Justice of Toren of The Radchaai Empire. Another interesting part is since the Radchaai language is genderless, the narrator constantly describes everyone as "she," but later you might discover that some character might be he. There are other small details here and there that narrator might say, but you start to question it as the story develops. In other words, Ann Leckie has done a stylish job of show-and-not-tell about the world that she's built.

For AdoptOpenJDK JDK 8:

docker pull eed3si9n/sbt:jdk8-alpine
docker run -it --mount src="$(pwd)",target=/opt/workspace,type=bind eed3si9n/sbt:jdk8-alpine

For AdoptOpenJDK JDK 11:

docker pull eed3si9n/sbt:jdk11-alpine
docker run -it --mount src="$(pwd)",target=/opt/workspace,type=bind eed3si9n/sbt:jdk11-alpine

Over the holiday break I've implemented left TOC for Pamflet, and released it as Pamflet 0.8.0.

As of Scala 2.13.0-M5, it's planned that scala.Seq will change from scala.collection.Seq to scala.collection.immutable.Seq. Scala 2.13 collections rework explains a bit about why it's been non-immutable historically. Between the lines, I think it's saying that we should celebrate that scala.Seq will now be immutable out of the box.

Defaulting to immutable sequence would be good for apps and fresh code. The situation is a bit more complicated for library authors.

• If you have a cross-built library, and
• if your users are using your library from multiple Scala versions
• and your users are using Array(...)

this change to immutable Seq could be a breaking change to your API.

Spotify: https://open.spotify.com/user/1235450353/playlist/1cOJUEKtQfCKAovwSZhdyh...
YouTube: https://www.youtube.com/playlist?list=PLSUh6oJ5ZotVgnwc5xG-mE2uiunHANOyY

3 h 28 min

track list

• Nobody But You - George FitzGerald, Hudson Scott
• Nothing To Lose - Giorgia Angiuli
• Bellyache (Marian Hill Remix) - Billie Eilish, Marian Hill
• Technicolour - Mansionair
• Come Home - BAYNK, Shallou
• asleep (feat. MOONZz) - pluko, MOONZz